1935 Mercedes-Benz 500/540 K Cabriolet A and Concours-Winning Cadillac V-16s Lead the Groendyke Collection at RM Sotheby's Arizona Auction

SCOTTSDALE, ARIZONA — SCOTTSDALE, Ariz., Nov. 10, 2026 – RM Sotheby’s will offer 13 automobiles from The Groendyke Collection at its Arizona auction in January 2027, led by a 1935 Mercedes-Benz 500/540 K Cabriolet A. Bringing together rare coachwork, notable provenance, and concours-winning restorations, the offering celebrates the remarkable collecting legacy of the late John D. Groendyke, whose passion for extraordinary automobiles and pursuit of excellence

Throughout his collecting career, Groendyke owned hundreds of automobiles, including some of the rarest and most significant pre-war American classics ever produced, alongside a select group of European marques, particularly Mercedes-Benz.

“John was more than a longtime client. He was a dear friend and someone who had been part of the RM Sotheby’s family for more than 30 years,” said Gord Duff, president of RM Sotheby’s. “He had an extraordinary eye for great cars, particularly the finest pre-war American automobiles, and his standards were incredibly high. If a car wasn’t already among the best, he made sure it became one of the best. But what I’ll remember most is his kindness, his enthusiasm, and the genuine joy he found in collecting. He was always looking for that next special car, and it was a privilege to share that passion with him over the years. There will never be another John Groendyke, and we’re honored to bring these remarkable automobiles to the next generation of collectors.”

Known for his exceptional eye and uncompromising standards, Groendyke sought out the finest examples of the automobiles he admired. When a car did not meet his expectations, he devoted the time and resources necessary to bring it to concours-winning condition. He was a fixture at the Pebble Beach Concours d’Elegance, attending with an automobile for approximately 30 years, and his restorations earned numerous awards at Pebble Beach, Amelia Island, and the Concours of America.

Groendyke also had a particular enthusiasm for building collections within his collection. Over the years, he assembled complete groups of Chrysler letter-series cars and 1950s Cadillacs, as well as an extraordinary collection of more than 25 Cadillac V-16s representing many of the marque’s most desirable 1930s body styles. His collection typically numbered between 30 and 50 automobiles at any given time, but it was constantly evolving, with new acquisitions, occasional trades, and even the return of cars he had previously owned. For Groendyke, the pursuit was as much a part of the enjoyment as the ownership itself.

The collection’s presentation in Arizona is particularly fitting. Groendyke maintained a second home in the state for many years and was a regular attendee of RM Sotheby’s Scottsdale auctions from their inception. The January offering represents an opportunity for collectors to acquire automobiles from one of the most respected and thoughtfully assembled collections of American and European classics.

Leading the collection is the 1935 Mercedes-Benz 500/540 K Cabriolet A by Sindelfingen, one of just 33 examples produced as a 500 K Cabriolet A. Factory-upgraded with a 5.4-liter engine before delivery to violinist and composer Adolf Busch in 1935, it retains that engine today. Later owned by American socialite and fashion icon Millicent Rogers, the car was discovered on a French farm around 1960 by a US Air Force pilot who brought it to the United States. Presented in black with red leather upholstery and a mother-of-pearl dashboard, it has been shown twice at Pebble Beach, earned class wins at Amelia Island and ModaMiami, and completed the 1,000-mile Colorado Grand (Estimate: $3,750,000 - $4,500,000 USD).

The Arizona offering provides a compelling view into Groendyke’s passion, particularly through its selection of Cadillac’s flagship V-16 models. Leading the Cadillac group is the 1936 Cadillac V-16 Convertible Coupe by Fleetwood, restored by Steve Babinsky’s Automotive Restorations and awarded first in class at the 2019 Pebble Beach Concours d’Elegance (Estimate: $1,600,000 - $2,000,000 USD).

Equally compelling is the 1930 Cadillac V-16 All-Weather Convertible Sedan by Murphy, wearing a one-off body created in period by the Pasadena coachbuilder. Purchased new by Charles S. Howard Jr., the Cadillac later resided in the Mozart and Andrews collections before joining The Groendyke Collection. It has appeared at the Pebble Beach Concours d’Elegance multiple times, earning a first-in-class award (Estimate: $1,000,000 - $1,500,000 USD).

The 1933 Cadillac V-16 Convertible Coupe by Fleetwood adds both rarity and a connection to motion-picture history. The 117th of 126 Cadillac V-16s built for 1933, it is believed to be one of only two surviving examples of its body style. Its original owner, inventor Theodore W. Case, developed Movietone, a system that synchronized sound with motion pictures. Sold new through Lewis E. Springer’s Cadillac dealership in Auburn, New York, the car has also been shown at Pebble Beach (Estimate: $800,000 - $1,000,000 USD).

Also featured is a 1930 Cadillac V-16 Roadster by Fleetwood, formerly of the Frank and Milli Ricciardelli Collection. Presented with a beautiful older restoration in a charming color combination, it joins the other featured Cadillacs in being recognized as a Full Classic by the Classic Car Club of America (Estimate: $850,000 - $1,050,000 USD).

Beyond the Cadillacs, the 1936 Auburn 852 Supercharged Speedster stands among the collection’s highlights. An authentic example of the celebrated design, it retains its original body, frame, engine, and firewall serial-number tag, supported by Auburn Cord Duesenberg Club Category One certification. Beautifully restored and a multiple award winner, it was formerly owned by Ted Billing, David Tunick, and James Foght (Estimate: $800,000 - $1,000,000 USD).

A 1937 Cord 812 Cabriolet, concours restored by the ACD specialists at Brian Joseph and also carrying ACD Club Category One certification, adds another distinctive American design to the offering. Like the Auburn, it is recognized as a CCCA Full Classic (Estimate: $250,000 - $350,000 USD).

The Entire Groendyke Collection
Listed in descending order of estimated value.

1935 Mercedes-Benz 500/540 K Cabriolet A by Sindelfingen — $3,750,000 - $4,500,000 USD
1936 Cadillac V-16 Convertible Coupe by Fleetwood — $1,600,000 - $2,000,000 USD
1930 Cadillac V-16 All-Weather Convertible Sedan by Murphy — $1,000,000 - $1,500,000 USD
1930 Cadillac V-16 Roadster by Fleetwood — $850,000 - $1,050,000 USD
1936 Auburn 852 Supercharged Speedster — $800,000 - $1,000,000 USD
1933 Cadillac V-16 Convertible Coupe by Fleetwood — $800,000 - $1,000,000 USD
1932 Marmon Sixteen Victoria Coupe by LeBaron — $300,000 - $450,000 USD
1938 Cadillac V-16 Convertible Coupe by Fleetwood — $250,000 - $350,000 USD
1937 Cord 812 Cabriolet — $250,000 - $350,000 USD
1929 Rolls-Royce Phantom I Ascot Tourer in the style of Brewster  — $150,000 - $200,000 USD
1956 Ford Thunderbird — $60,000 - $80,000 USD
1949 Cadillac Series 62 Club Coupe — $60,000 - $80,000 USD
2006 Maybach 57S — $30,000 - $50,000 USD